She was the first athlete to be suspended at the ongoing Games, which will run till Feb. 26. Pyleva, 30, came second in the 15km biathlon on Sunday.
The substance found in the Russian's anti-doping test was reportedly a Russian-made stimulant. Pyleva was suspended by the International Olympic Committee anddid not take part in Thursday's biathlon sprint.
She faces a ban if a second test on the same sample comes out positive too. Pyleva is one of the world's top biathletes.
She won a gold in the biathlon pursuit at the 2002 Winter Gamesin Salt Lake City. She also won the 2004 World Championship individual gold at Obersdorf, reports the AP.
Ukrainian President Vladimir Zelensky fears that his country may split into two similarly to the Korean scenario.